One goal of functional genomic research is to accelerate the improvement of plants used for food, pharmaceuticals, ornamentals, biofuels, biopower, biochemicals, carbon sequestration, and materials. Many functional genomic research programs focus on how changes to individual genes affect a plant's root system. Such programs generally apply high-throughput, large-scale experimental methodologies combined with statistical and computational analysis of the results. It is not unusual for tens of thousands of plant specimens to be studied in order to deduce the function of a single gene in the plant. In these types of research programs, the ability to analyze plant root structure and function in a timely, cost efficient manner is vital.
High-throughput cost efficient root imaging is also needed in root growth research programs and in the screening of cultivars developed through traditional breeding programs.
A destructive method of studying plant roots consists of taking the plant and its surrounding soil out of the container in which it was growing, washing the soil from the plant roots, and imaging the roots using a desktop flatbed scanner.
Another method for imaging plant roots is performed using devices called rhizotrons. These are transparent tubes that are placed in the ground. After plant roots grow around the rhizotron, a visible light camera is placed in the tube for capturing images of the plant roots that are on the external surface of the rhizotron.
Another method uses computed x-ray tomography to acquire several hundred high energy x-ray images of the roots taken at slightly different angles. Special computer algorithms are used to reconstruct an approximate three-dimensional image of the root system. With this method approximate root structure information can be extracted even though the roots are hidden by surrounding soil. The technique requires that the soil be specially processed to be highly homogeneous in both size and composition. The penalty one pays for this capability is the need for many images, thus precluding high throughput performance and providing lower resolution.
Yet another method is to grow plants in custom growth chambers i.e., between two transparent sheets with transparent glass beads as a substrate and use traditional visual imaging technology.
None of these prior methods provide a nondestructive high-throughput technology that supports large-scale plant root characterization studies. Thus, there is a need for a high resolution, high throughput, nondestructive, noninvasive root characterization system.